U.S. Pat. No. 3,778,396 discloses a rubber composition comprising rubber reinforced by distributing therein carbon fibers, carbon black and softener. Vulcanized rubbers made from this rubber composition are disclosed as being useful for tires and conveyor belts.
U.S. Pat. No. 4,740,192 discloses a power transmission belt wherein a portion thereof is formed as a composition of 1 to 100 parts by weight of whiskers distributed in 100 parts by weight of rubber. The whiskers may be formed of one or more of alpha-silicon carbide, beta-silicon carbide, silicon nitride, alpha-alumina, titanium oxide, zinc oxide, tin oxide, graphite, iron, copper or nickel. Where cut fiber is utilized, it may be formed of cotton, nylon and polyester.
U.S. Pat. Nos. 4,509,938 and 4,571,230 disclose a power transmission belt where the tension section and the compression section have a plurality of randomly arranged fibers embedded in the compounds with the axes of the fibers being disposed substantially traversed to the longitudinal axis of the belt.
U.S. Pat. No. 4,808,149 relate to a power transmission belt, which may contain zero to 30 phr of a fiber such as polyaramide or graphite, having a length of from 20 to 42 microns in length.